If everyone was to keep their spot in spawn loaded we would have all of spawn loaded all the time. Although I don't know, maybe this is already more or less the case due to some player typically being logged in there at any given time anyway?

The amount of chunks one player keeps active (just in their view distance), means that most of Spawn City is kept loaded all the time.

One of the advantages we wanted with the city layout was more interaction with players (instead of everyone going their separate ways and never seeing each other), the disadvantage of course is it centers all the lag to the one spot, because everyone is in the one area (more or less)....